staging: lustre: Make LUSTRE_LLITE_LLOOP tristate

There seems to be no reason why it can't be a module; in fact that is
currently supposed to be the default.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/Kconfig

@@ -55,6 +55,6 @@ config LUSTRE_TRANSLATE_ERRNOS
 	default y
 
 config LUSTRE_LLITE_LLOOP
-	bool "Lustre virtual block device"
+	tristate "Lustre virtual block device"
 	depends on LUSTRE_FS && BLOCK
 	default m